A single source reference on tropical weather predictions. With a traditional focus on the upper Texas and Louisiana Gulf Coast we've maintained links to track all Atlantic Basin, Caribbean and eastern Pacific storm systems.
We are now expanding our view to tropical storms throughout the world intending to be a comprehensive global storm tracking resource.

Tuesday, April 03, 2007

The forecasts for 2007 are already coming in and are even being modified 2 months in advance of the Atlantic hurricane season.

Back in December, Dr. William Gray's team at the University of Colorado originally predicted 14 named storms including 7 hurricanes, three of which are expected to be major (Cat 3+). Today the team revised its predictions upward. Seventeen tropical systems are expected to grow into named storms with nine hurricanes and five major hurricanes.

The increased storm activity includes both an increase in the number of storms and the intensity of those storms. There are two primary causes for this increased activity, the multidecadal oscillation and the presence of La Nina in the Pacific Ocean.

Officials at the National Oceanic and Atmospheric Administration announced the official end of a brief and mild El Nino that started last year. That El Nino was credited with partially shutting down last summer's Atlantic hurricane activity in the midst of what was supposed to be a busy season.

“We're seeing a shift to the La Nina, it's clearly in the data,'' NOAA Administrator Conrad Lautenbacher said. La Nina, a cooling of the mid-Pacific equatorial region, has not officially begun because it's a process with several months with specific temperature thresholds, but the trend is obvious based on satellite and ocean measurement data, he said.

“It certainly won't be welcome news for those living off the coast right now,'' Lautenbacher said. But he said that doesn't mean Atlantic seaboard residents should sell their homes.

Forecasters don't know how strong this La Nina will be. However, it typically means more hurricanes in the Atlantic, fewer in the Pacific, less rain and more heat for the already drought-stricken South, and a milder spring and summer in the north, Lautenbacher said. The central plains of the United States tend be drier in the fall during La Ninas, while the Pacific Northwest tends to be wetter in the late fall and early winter.

We discussed this last month when NOAA announced the likely build-up of La Nina conditions:

This year, expect to see a disclaimer in every article discussing the prediction for the 2007 tropical season.

Forecasts for 2006, by Gray's team and another by government meteorologists, also predicted an active hurricane season, but only 10 named storms developed and only 5 of those became hurricanes. By all accounts, the forecasts were wrong. Meteorologists said later on that a strong El Niño event weakened storm activity. The energy from El Niño starts with a huge, warmer-than-normal "bathtub" of seawater that races from west to east in the Pacific and across the continent and eventually results in atmospheric energy that shears the tops off Atlantic storms before they can really intensify.

But forecasters now say that El Niño shouldn’t be a factor this year, so hurricane activity will be enhanced.

The facts are that El Nino is very hard to predict and Dr. Gray's team has been very accurate. The media will hold on to anything that demonstrates that the experts might be wrong. Weather patterns are complex chaotic systems that defy prediction. This forecast is likely to be accurate and we who live on the coast need to be prepared for an active season. If another mild season surprises us then we are so lucky but if we become cavalier then a minor storm could turn into a catastrophe.